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610 THE CRINOIDEA CAMERATA OF NORTH AMERICA. 
Basals forming a shallow cup, the sides gradually expanding but not 
thickened; the upper margins distinctly angular. Radials large, fully as 
long as wide. Costals one half smaller, almost as wide as long. Palmars 
quite small, the two inner ones of each ray giving off two arms, the outer 
ones but one. Arm bases a little projecting, the facets moderately large and 
concave; arm openings arranged in groups, those of adjoining rays twice 
as far apart as those within the ray. Respiratory pores slit-like. Structure 
of the arms unknown. Regular interbrachials: 1, 2, 2,1, succeeded by a 
small elongate piece, wedged in between the arm-bearing brachials; the 
first as large as the costals, those of the second row equal in size to the 
distichals. The anal plate, which is as wide at the bottom as near the top, 
is followed by 2, 3, 2, and 2 plates, the latter generally supporting two small 
elongate pieces, which are in contact with the interambulacrals. ‘The 
interdistichal spaces are deeply depressed, and occupied by a single flat 
piece. Ventral disk subconical, gradually passing into the anal tube, which 
is almost central, and very stout. The disk, as well as the tube, 1s composed 
of an immense number of all sorts of plates; some of them are large and 
take the form of elongate nodes or small spines, others are smaller and have 
rounded nodes; while the smallest ones, which are interspersed profusely 
between the larger, are simply convex. Orals extremely excentric, small, 
and separated by small plates; the posterior one, which stands erect and 
bears a transverse node, takes part in the tube. Radial dome plates sub- 
spinous, irregularly arranged, and placed at some distance from the arm 
bases. 
Horizon and Locality. — Lower Burlington limestone; Burlington, Iowa. 
Type in the Museum of Comparative Zoélogy. 
~ Remarks. — Meek and Worthen’s figure in the Illinois Report is some- 
what misleading; the plates of this species are generally less convex, the 
suture lines almost obsolete, and the radiating ridges upon the plates more 
distinct than shown in that figure. 
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oneal 
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